Enforce restricted # pool txs served via RPC + optimize chunked reqs [release-v0.18]

- `/getblocks.bin` respects the `RESTRICTED_TX_COUNT` (=100) when
returning pool txs via a restricted RPC daemon.
- A restricted RPC daemon includes a max of `RESTRICTED_TX_COUNT` txs
in the `added_pool_txs` field, and returns any remaining pool hashes
in the `remaining_added_pool_txids` field. The client then requests
the remaining txs via `/gettransactions` in chunks.
- `/gettransactions` no longer does expensive no-ops for ALL pool txs
if the client requests a subset of pool txs. Instead it searches for
the txs the client explicitly requests.
- Reset `m_pool_info_query_time` when a user:
  (1) rescans the chain (so the wallet re-requests the whole pool)
  (2) changes the daemon their wallets points to (a new daemon would
      have a different view of the pool)
- `/getblocks.bin` respects the `req.prune` field when returning
pool txs.
- Pool extension fields in response to `/getblocks.bin` are optional
with default 0'd values.

src/cryptonote_core/blockchain.cpp

@@ -2065,7 +2065,7 @@ bool Blockchain::handle_alternative_block(const block& b, const crypto::hash& id
       cryptonote::blobdata blob;
       if (m_tx_pool.have_tx(txid, relay_category::legacy))
       {
-        if (m_tx_pool.get_transaction_info(txid, td))
+        if (m_tx_pool.get_transaction_info(txid, td, true/*include_sensitive_data*/))
         {
           bei.block_cumulative_weight += td.weight;
         }